When a CT (computed tomography) scanner is used to scan a patient's thoracic or abdominal viscera, the patient's respiration may cause distortion of CT images. To eliminate this distortion, the concept of four-dimensional CT (4D CT) was proposed. For 4D CT, it is critical to measure the patient's respiratory cycles accurately.
In the existing methods of measuring respiratory cycles with a CT scanner, a marker may be placed on the body of the patient, which marker may move with the patient's respiration, such that a respiratory cycle curve may be formulated by tracking positions of the marker via CT scans.
We find that there is still room for further reducing the radiation dose of X-rays when the above-described methods are adopted to measure respiratory curves.
Therefore, an embodiment of the present invention provides method and apparatus for reducing radiation from CT measurement of respiratory cycles and a corresponding CT scanner, such that when the CT scanner is used to track the marker for respiratory cycle measurement, the radiation dose of X-rays from the CT tube can be further lowered.